Hi i have a 94 Mustang GT and i have the SLP stage 1 I really like it. It sounds so good but i just put a Mac off road X pipe on now its way to loud, so can i put mufflers on to quit it down and make it sound good again or will i have to put my stock H pipe back on. Can anyone help me out. Thank you Kevin.

P.S. The only reason I put the X pipe on because i'm going to supercharger it soon.

Pretty much any other muffler would quiet it down because that SLP system really rips.  The one I heard hurt my ears.  If you want a really good sound but not sound like every other horse, get the Flowmaster Super 40, part # 952548.  You might need to change the pipes because the SLP uses resonators and the pipes may not line up.   

Cool thank you. What would be the best set up for my car. I am doing to put a procharger D1 on in about 2 weeks or so. I'm thinking about doing the top end of the motor soon after. What would be a good combo like (Heads, Cam, Intakes)? Thanks Eagle  

With a '94, the top end of the engine can be wide open.  Your only real limitation is the size of your wallet.  I would go with any of these: HEADS: TFS Twisted Wedge, TFS High Port, TFS Track Heat, Dart 195, AFR 185, Edelbrock Performer RPM, or World Windsor Lite.   INTAKES: Holley Systemax II, TFS Track Heat, BBK, GT40, Weiand Stealth (just like the Holley), Edelbrock RPM, or Edelbrock RPM II.  CAMS: go with the Comp Cams Xtreme line or even the Nitrous XP line.  Lunati has a great cam that will work with your factory '94 computer and it's a remake of their old 1087 cam.  If you get too crazy with a cam with that '94 computer, it'll argue with you.  It's a finicky pain in the ass sometimes so a computer tune will definately be needed.  Overall, you'll need a cam with around a 114-116 degree lobe separation.  I gave you the best parts that will match with the ProCharger you're getting.  You definately need to retune the whole thing if you install the supercharger before the cam/head/intake combo.  You'll even see a decrease in boost because you inproved the airflow so much that it'll lose velocity.  You don't have to get crazy with trying to get that boost back right away.  Make sure you have enough fuel for it.  Get a 255 lph pump, a Canton fuel filter and then some better rails.  And lastly, get some ARP studs, they help hold the boost better than even the ARP bolts do.

Thank you for all that help. Sorry well here i go again where can i get a dart block. I would like a 331 short block. How much I'm I looking at for one. If you can help that would be gaeat. Thank you Kevin

You'll be looking at about $2000 before any machine work is done.  OUCH!!!  But it'll almost be bulletproof and worth it if you're going to have over 1000 hp or outright racing.  For a street car, you may not need it but would be worth it just for the assurance nothing wil break.  Check out DSS, Bennett Racing, or Dart themselves for any other distributor.   

Hey about your loudness priblem, the x pipe acts like a resonance chamber and makes your car louder. I am running a BBK x pipe with flowmasters and I really like the deep tone.

Also my dad liked mine so much that he got a set for his 88 GT.